Got a good 90 minute hard practice session in. The short and sweet: It plays like an average round poly.
RPM Power has a bit more than average power on shots where the swing path is primarily straight through the ball. I could not get the strings to grip the ball when I tried to swing significantly upward or downward at the ball, and in those instances the ball speed was greatly reduced and the launch angle became very low even though I hit the sweet spot. Some skimming type shots that with S7T would clear the net by six feet and land near the baseline, would clear the net by just a couple of feet and land at the service "T". It is that much of a difference. It takes a concerted effort to both swing upward and forward through the ball and once I got the hang of that, I was able to get more net clearance and decent topspin.
On regular groundstrokes, my son said it appeared I had about 30% less topspin in general, and I never once was able to hit a ball which kicked up hard and high at him to cause him trouble. Underspin backhands were hard to get deep - the ones I hit were floaty and slow. After the first ten minutes when the balls got a bit fluffy, it felt like it became increasing difficult to dig the strings into the felt and get grip. Any time I didn't swing through the ball, it ended up in the net. There was also a lot of material transfer from the string to the ball, probably on the more skimming type shots where it just doesn't feel like the strings ever get a full and complete bite on the felt.
There's a little bit of give on the initial contact, and then RPM Power firms up. It's not that crisp, but is more comfortable than average both hitting the sweetspot and missing the sweetspot.
Volleys were a piece of cake. There's minimal sensitivity to incoming spin so it takes almost no adjustment when punching through topspin or underspin shots. Touch was good and it seemed easy to take speed off the ball and hit a short angle.
RPM Power makes a loud, high pitched "thwack" on contact. It actually sounds like I'm really crushing the ball even on more moderate swings. Control seems about average for a round string and better than a shaped poly. The spin insensitivity meant I could take pretty much the same swing on any incoming groundstroke and the ball would go where I aimed it.
Compared to the other round strings I've recently used, which were Kirschbaum Proline Evolution, Dunlop Xplosive Red, and Diadem Flash, RPM Power feels less crisp than Proline Evo and Flash, and seems reminiscent of what I remember of Xplosive Red. Overall, it's probably the most comfortable of these four strings. Power levels may be a little bit higher than any of the other three. Control and sensitivity to incoming ball spin seem about the same as these other three strings. I do remember having a difficult time with any of the round strings when transitioning from a moderate topspin groundstroke to a maximum topspin groundstroke, but I don't remember having as striking of a difference in launch angle and ball speed as with the RPM Power.
There is light notching of the mains in the sweetspot area. The strings did return to position the entire time. There seems to be a bit more tension loss, but playability on flatter shots remained consistent throughout the 90 minutes.
Near the end of the practice, I pulled out my other racquet with S7T. Compared to RPM Power, S7T has more power, is more crisp, and has significantly better bite on the ball. The ball trajectory had a lot more shape with the same swingpath, and the bounce was a foot or more higher. The launch angle is quite a bit higher with S7T. I immediately regained the ability to hit high loopy heavy topspin shots, and slice shots had their previous low and penetrating trajectory.
I watched Thiem play Berretini today with these strings and at least from the TV shots I can't tell that he has lost any spin. He didn't hit many of his extreme kick serves on the ad side, but his groundstrokes seem to have the same shape and bounce as he always had. I don't have the racquet head speed, swingpath, or swing mechanics to be able to replicate the shots I can create with S7T.
I'll be playing some doubles over the next few days. In the past while testing round strings, I found they suited me playing doubles because I tried only to hit low, controlled shots with minimal spin. It will also give me a chance to see how RPM Power affects my serving ability.
Impressions for now are not favorable. I prefer the way that shaped polys play. Among the round polys I've tried, I would prefer Proline Evo and Flash over RPM Rough at this time.
More later after I get a few more hours in.
